VPN firewall help !!!

ipconfig.all

Hello.

I use RRAS (PPTP) as my VPN Server. When remote clients connect to the network remotely I want them to just be able to RDP the computers in the network and not have access to any other ports in the network. For an example lets say a remote person VPN in and I just want them to be able to use the RDP protocol only I do not want the client VPN machines to access files in other computers or look at other websites in the network I just want them to have RDP only.

How can I do this, I looked at IP filters but that just filters IP's not pots.

Any advice or tutorials?

THX.